Key Features
Technical Specifications
General
Electrical
Digital Inputs
High-Speed Counter Performance
Filter Times
Isolation & Environmental
Certifications
Pin Assignment
The SB 1221 uses a 6-pin connector (X19) for field wiring :
Applications
The SB 1221 24 V DC is ideal for applications requiring high-speed digital signal acquisition:
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High-Speed Counting: Position and velocity feedback from incremental encoders
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Material Handling: High-speed sorting and detection systems
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Precision Motion Control: Quadrature encoder input for servo and stepper systems
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Packaging Machinery: High-speed product counting and registration
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General Manufacturing: Signal processing from 24 V DC industrial sensors requiring fast response
Key Benefits
Important Notes
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Source-Type Inputs Only: The inputs support current-sourcing (PNP/source) configurations only. They are M-reading, meaning the logical state is "1" when the input is pulled to 0 V (ground) .
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Signal Board Form Factor: The SB 1221 plugs directly into the S7-1200 CPU. It is not a standalone module that mounts on a DIN rail.
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Square Wave Requirement: For switching frequencies above 20 kHz, the digital inputs require a clean square wave signal. Minimize cable length, use high-quality shielded cable, and consider external load resistors if signal integrity issues arise .
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Cable Shielding: Always use shielded twisted pair cable with a maximum length of 50 m for reliable high-frequency performance .
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Power Supply: The module draws power from the CPU backplane (5 V DC, 40 mA). No external power supply is required for the module itself, but the field signals must be provided externally .
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TIA Portal Configuration: Configure the module in TIA Portal using the device configuration. For HSC applications, assign the appropriate HSC channels to the inputs.
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Simultaneous Inputs: At 60°C horizontal installation, only 2 non-adjacent inputs can be ON simultaneously. All 4 inputs can be ON at 55°C horizontal or 45°C vertical .
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5 V DC Variant: For 5 V DC applications, refer to the 6ES7221-3AD30-0XB0 variant .
FAQ
Q1: What is the primary function of the 6ES7221-3BD30-0XB0?
A: It is a SB 1221 signal board that adds 4 high-speed digital inputs to a SIMATIC S7-1200 PLC. It operates on 24 V DC and supports input frequencies up to 200 kHz, making it suitable for high-speed counting and positioning applications .
Q2: What is the difference between the 6ES7221-3BD30-0XB0 and 6ES7221-3AD30-0XB0?
A: The key difference is the input voltage: the 3BD30 variant operates on 24 V DC, while the 3AD30 variant operates on 5 V DC. Both offer 4 inputs at 200 kHz .
Q3: What type of inputs does this module have?
A: The inputs are current-sourcing (source-type) only. They are M-reading, which means the logical state is "1" when the input is pulled to 0 V (ground) .
Q4: What is the maximum input frequency?
A: The maximum input frequency is 200 kHz for single-phase signals and 160 kHz for quadrature phase (encoder) signals .
Q5: Does this module require an external power supply?
A: No. The module draws power from the CPU backplane bus (5 V DC, 40 mA typical). However, the field input signals must be provided externally from your sensor or signal source .
Q6: What is the cable length limit?
A: The maximum cable length is 50 meters using shielded twisted pair cable .
Q7: What is the power loss of this module?
A: The typical power loss is 1.5 W .
Q8: What are the physical dimensions and weight?
A: The module measures 38 mm × 62 mm × 21 mm and weighs approximately 35 grams .
Q9: What is the maximum number of inputs that can be ON simultaneously?
A: At 60°C horizontal installation, only 2 non-adjacent inputs can be ON simultaneously. All 4 inputs can be ON at 55°C horizontal or 45°C vertical installation .
Q10: What certifications does this module hold?
A: The module is certified with CE, cULus, FM, CSA, and Marine approvals, ensuring global compliance .
